It is known in the art that magnetics can be used to determine the position of an object relative to a fixed point. In this respect, Hendrickson U.S. Pat. No. 4,728,950 discloses a remote monitoring device that utilizes magnetics to determine the position of the needles in a utility meter. Hendrickson determines the position of the meter by utilizing ten sensors circumferentially spaced about the needle axis and a magnetized needle. The position of the needle can be determined when the needle is positioned under one of the sensors. As can be appreciated, the magnetic on the needle must be spaced from the needle axis such that the magnetic passes by the sensor as the needle rotates. When the magnetic portion of the needle passes a sensor, the position of the needle is detected. However, when the needle is between sensors, the presence of the needle is not fully detected and assumptions must be made about the position of the needle. As a result, while Hendrickson is capable of determining the position of the needle, accuracy is suspect and assumptions must be made for the needles which are not positioned in range of one of the ten sensors. Hendrickson's device is also expensive in that it needs ten sensors for every needle. When a four needle meter needs to be monitored, 40 sensors are needed. In addition, as is shown, the sensors must be placed at a point space from the needle axis such that the monitoring device blocks the gauges thereby preventing the meter to be read except by the monitoring system. This can make trouble shooting the system difficult and costly and can prevent quick verification that the system is functioning properly.
Schenk, Jr., U.S. Pat. No. 6,742,396 overcomes some of the accuracy and readability shortfalls of Hendrickson by utilizing a variable monitoring technique that has an external readable portion. In this respect, Schenk, Jr. discloses a dial indicator that utilizes magnets to couple the meter's dial needle to a rotating measuring device. This system is not a magnetic sensing system. Conversely, the magnets merely couple the moving parts of the sensing system to the meter's needle such that a sensing system follows the dial needle as it rotates. Thus, Schenk's device requires moving parts to monitor the meter. Further, the magnetic strength necessary to physically lock the moving parts of the sensor to the meter's needle is greater than that which is necessary for non-mechanical devices due to inevitable friction between the moving parts. Friction in the monitoring sensor can also cause the monitoring device to become disconnected with the meter's dial. If this takes place, the output of the remote monitoring device is worthless. As can be appreciated, the remote monitoring device is of little value unless it can be relied upon by the end user. The longevity of Schenk is also suspect in that the monitoring device is in constant motion and internal components can wear. Yet another problem with Schenk's device is that the moving parts of his sensor are not capable of continued rotation. Conversely, Schenk's device can not rotate more than 360 degrees which prevents it from being used on many meters.
Both Schenk and Hendrickson do not allow sufficient visual inspect of the actual dials or needles. In this respect, gas companies, and other utilities, are required to verify the accuracy of meter readings. This requirement necessitates a periodic visual inspection of the meter. Hendrickson prevents a visual inspection of the dials since his system completely covers the meter's dials. As a result, a visual inspection requires his system to be at least partially removed from the meter. As can be appreciated, periodic removal of the sensing system is expensive and can damage the unit. While Schenk provides a means for inspecting the position of the needle on site, the actual needle is still not visible whereby confirmation that the system is producing an accurate reading also requires removal of the system from the meter.